1. Field of the Invention
The present invention relates generally to an analyzer instrument, and more particularly, concerns a detector assembly for use in an instrument for detecting light associated with the chemical, immunochemical or biological testing of samples.
2. Description of the Prior Art
Automatic analyzer instruments are presently used for a variety of chemical, immunochemical and biological tests for substances in samples. The use of radiant energy from a light source, such as a lamp, to establish a basis for the analysis of the samples is quite prevalent in presently known and available automatic analyzers. When a light source is employed in such analyzers, the test liquid may be monitored for a number of light-associated responses including colorimetric, fluorometric, nephelometric or light scatter, absorbance and the like.
In automatic analyzers, particularly those using radiant energy from a light source for analysis purposes, it is desirable to perform a test on many samples in a single run of the equipment. To facilitate the testing of multiple samples, many analyzers use a carousel or a turntable for holding the samples, usually in liquid form, to be analyzed. The sample liquid is typically carried in different kinds of vehicles, including tubes, cuvettes, bags, cups and the like carriers. In an automatic analyzer which employs a carousel or turntable, along with a light source for analysis purposes, some mechanism is generally provided for passing each test sample before the light source so that individual analysis of the test samples may be achieved. Representative instruments of the aforementioned type are described in U.S. Pat. No. 4,483,927 and by DeGrella et al. in "A Nephelometry System for the Abbott TDx.TM. Analyzer," Clin. Chem. 31/9, 1474-1477 (1985).
In many instances, the carriers which hold the liquid sample for analysis have circular cross-sections, such as test tubes or cups. These round sample carriers introduce the possibility of inaccuracies in the detection system. Specifically, when the light beam is directed at a rounded surface surrounding the test sample, positional variations in the test tube could result in diminished efficiency of the light signal due to undesirable refraction of the light beam. Of course, positional variations of the carrier of the test sample could occur whether or not the carrier has a rounded cross-section; it is emphasized here that rounded tubes or cups introduce the possibility of magnifying the inaccuracies due to positional variations. Corrections for positional and temporal variations in the test sample carrier may be made by reliance on a reference standard associated with the light signal and by use of a ratio of measured signal and reference signal. One such approach for a corrected result, to eliminate positional and temporal variations, is described in the aforementioned article by DeGrella et al. However, short of using reference signals and ratios, which complicate the instrument and the electrical circuitry therefor, improvements are still being sought in eliminating positional variations of the test sample carrier, from the physical location standpoint, so that inaccuracies of the detection system may be minimized.
In addition to the just-mentioned improvements, it is also desirable, particularly with an automatic analyzer instrument, to be able to conduct the light analysis of the sample at different wavelengths on an automatic basis. For example, during a single run of the multiple test tubes in the instrument, it is frequently desirable to be able to detect different colorimetric or fluorometric responses of the samples. Since interference filters are commonly employed to provide selective wavelength analysis of test samples, many instruments require the changing of these filters, in the middle of a test run, in order to conduct multiple wavelength analysis. Implementation of an automated optical system for providing multiple and selective wavelength analysis would facilitate the efficiency of the analyzer instrument. It is toward the fulfillment of tthe above-described desiderata, and other features particularly relating to optical elements of automated analyzer instruments, that the present invention is directed.